Proëtus was a king of Tiryns and a son of Abas, the king of Argos, and Aglaia. His twin brother was Acrisius. He married Stheneboea (called Antia by Homer), who bore him three daughters, Lysippe, Iphinoë and Iphianassa, and one son, Megapenthes. His name seems to mean 'first', from protos, 'first' or proteion, 'first place', this being both a 'powerful' name and a suitable one for a king.